Traditional solid-state process

In the case of selective oxidation catalysis, the use of spectroscopy has provided critical Information about surface and solid state mechanisms. As Is well known( ), some of the most effective catalysts for selective oxidation of olefins are those based on bismuth molybdates. The Industrial significance of these catalysts stems from their unique ability to oxidize propylene and ammonia to acrylonitrile at high selectivity. Several key features of the surface mechanism of this catalytic process have recently been descrlbed(3-A). However, an understanding of the solid state transformations which occur on the catalyst surface or within the catalyst bulk under reaction conditions can only be deduced Indirectly by traditional probe molecule approaches. Direct Insights Into catalyst dynamics require the use of techniques which can probe the solid directly, preferably under reaction conditions. We have, therefore, examined several catalytlcally Important surface and solid state processes of bismuth molybdate based catalysts using multiple spectroscopic techniques Including Raman and Infrared spectroscopies, x-ray and neutron diffraction, and photoelectron spectroscopy. 

Hydrothermal routes Under ambient conditions, the low reaction temperature and fast precipitation rate have deleterious effect on the crystallization and optical performance of rare earth vanadate nanomaterials. Referring to traditional solid-state reactions, bulk YV04 Eu phosphors require a calcinations temperature above 1300 K, but it is too high for the preparation of nanomaterials. Alternatively, hydrothermal routes could provide the adequate energy for solution phase reactions, which have been widely described in preparation of ceramic powders. The high pressure and temperature largely promote the dissolution-reprecipitation process, so as to decrease the lattice defects of NCs. With fine modulation, this method is also efficient to produce nano-sized crystals. 

Flow chart of the mixed precipitation method is shown in Fig. 3.42. Briefly, alumina precursor powder was first synthesized by adding aluminum nitrate solution (0.15 M) dropwisely into the ammonium bicarbonate solution (1.5 M) under vigorous stirring. The as-prepared alumina precursor powder was then dispersed in yttrium nitrate solution to form uniform suspension. After that, ammonium bicarbonate solution (0.5 M) was added dropwisely into the suspension, so that yttrium precipitate was coated on the alumina precursor powder. The mixed precursor was aged, washed, dried, and then calcined to form yttrium aluminum garnet, with a phase formation temperature about 300 °C lower than that required by the traditional solid-state reaction process. Alternatively, it is also worth trying to coat yttria with alumina. 

Pt and Pd nitride nanoparticles have been synthesized by sputtering of the parent metal with N2 plasma [85]. Traditional solid-state synthesis techniques are often unsuccessful in creating Pt/Pd nitrides due to the low M-N bond strength. Physical vapor deposition processes such as sputtering can, however, often produce materials that are not expected thermodynamically due to the nature of the reaction. In this study, platinum and palladium thin films and nanoparticles were... 

Essentially all of the quirks and imperfections that make solid-state systems interesting— point defects, dislocations, grain boundaries, inclusions, voids, surfaces—fall within the scope of materials kinetics. This focus on solid-state processes and heterogeneity—what many would call microstructural development—is what makes materials kinetics unique. In order to tackle this topic, we will need to borrow a lot of concepts from chemical reaction kinetics, which we will cover in Chapter 3 of this textbook, but we will also learn many other concepts that are not usually covered in traditional chemical-based treatments of kinetics. In particular, we will spend a lot of time on solid-state diffusion and transport (Chapter 4). Compared to the gas and liquid phases, transport of matter in the solid phase tends to be slower and more difficult thus, atomic transport processes such as diffusion become much more important in determining kinetic behavior in solid-state systems. 

Kinetic studies have traditionally been extremely useful in characterizing several physical and chemical phenomena in organic, inorganic and metallic systems. It provides valuable qualitative, quantitative and kinetic information on phase transformations, solid state precipitation, crystallization, oxidation and decomposition. Unfortunately, no single reference comprehensively presents non-isothermal kinetic analysis method for the study of complex processes, determining the actual mechanism and kinetic parameters. This book provides a new method for non-isothermal kinetics and its application in heterogeneous solid state processes. In the backdrop of limitations in existing methods, this book presents a brief review of the widely used isothermal and non-isothermal kinetic analysis methods. 

Shock-compressed solids and shock-compression processes have been described in this book from a perspective of solid state physics and solid state chemistry. This viewpoint has been developed independently from the traditional emphasis on mechanical deformation as determined from measurements of shock and particle velocities, or from time-resolved wave profiles. The physical and chemical studies show that the mechanical descriptions provide an overly restrictive basis for identifying and quantifying shock processes in solids. These equations of state or strength investigations are certainly necessary to the description of shock-compressed matter, and are of great value, but they are not sufficient to develop a fundamental understanding of the processes. 

A study on the effectiveness of the E-plastomers as impact modifiers for iPP was carried out in relation to the traditional modifier EPDM. In this study, the flow properties of the E-plastomer-iPP and EPDM-PP blends were also evaluated. The blends were analyzed by solid-state 13C-nuclear magnetic resonance (NMR) spectroscopy, microscopy (SEM), and DSC. The results showed that E-plastomer-PP and EPDM-PP blends present a similar crystallization behavior, which resulted in a similar mechanical performance of the blends. However, the E-plastomer-PP blend presents lower torque values than the EPDM-PP blend, which indicates a better processibility when E-plastomer is used as an impact modifier for iPP. 

Although more than 100 individual process steps are used in the manufacture of even simple integrated circuits, the fabrication sequence invokes many of the same operations numerous times. A list of unit operations that compose the technological arsenal for the fabrication of solid-state materials and devices can be made. Clearly, these unit operations are distinctly different from those associated with traditional chemical manufacture. Nevertheless, the purpose of defining such a list is the same to establish the necessary chemical and physical operations so that a complicated process may be designed and carried out from individual, more easily controlled... 

Solid-state electrochemistry — is traditionally seen as that branch of electrochemistry which concerns (a) the -> charge transport processes in -> solid electrolytes, and (b) the electrode processes in - insertion electrodes (see also -> insertion electrochemistry). More recently, also any other electrochemical reactions of solid compounds and materials are considered as part of solid state electrochemistry. Solid-state electrochemical systems are of great importance in many fields of science and technology including -> batteries, - fuel cells, - electrocatalysis, -> photoelectrochemistry, - sensors, and - corrosion. There are many different experimental approaches and types of applicable compounds. In general, solid-state electrochemical studies can be performed on thin solid films (- surface-modified electrodes), microparticles (-> voltammetry of immobilized microparticles), and even with millimeter-size bulk materials immobilized on electrode surfaces or investigated with use of ultramicroelectrodes. The actual measurements can be performed with liquid or solid electrolytes. 

The classic treatment of carrier recombination can be related to the notion of the recombination time. The recombination time represents a combination of the carrier motion time (im), i.e. the time to get the carriers within capture radius (it is often assumed to be the Coulombic radius rc = e2/An o kT), and the elementary capture time (tc) for the ultimate recombination event (actual annihilation of charge carriers), tree1 = m1 -I Tc 1 (cf. Fig. 3). Following the traditional description of recombination processes in ionized gases, a Langevin-like [22] and Thomson-like [23] recombination can be defined if Tcsolid-states physics, these two cases have been distinguished... 

---